由探究加速度与力、质量的关系看高考物理力学实验

实验题是高考考查学生基本能力的重要手段,其考查角度已从基础知识层面逐步发展到综合性、应用性、创新性层面,考查变得非常灵活.本文结合探究加速度与力、质量的关系这一实验分析一下高考物理力学实验的考查趋势.

应用型人才培养背景下大学物理力学实验教学改革的创新思考

随着现代社会的不断进步与发展,应用型人才成为了现如今社会市场的需求群体。本文针对应用型人才培养背景下的大学物理力学实验教学的特点和现状,结合社会对人才培养的需求,并从如今的教学情况仍存在的诸多教学问题出发,针对应用型人才培养背景下的大学物理力学实验教学的内容、方法、教学评价等对其进行了创新性的思考,并提出相应的改进策略。

高中物理力学实验有效教学的探索

物理力学实验作为高中物理力学中一个重要的分支，其主要的目的就是让学生在实验的过程中感知物理力学公式的来源，让学生可以更加深刻的去体会物理力学习效率，并且有效的去培养学生对于物理力学的兴趣，提高学生在学习物理力学过程中的学习效率。但是学生在进行物理力学实验的学习的过程中往往会因为实验本身相对于枯燥从而失去了实验的兴趣，所以为了能够更好的去帮助学生学习物理力学实验，对如何提高物理力学在教学过程中的教学效率进行研究是十分必要的，本文主要针对这一问题进行相关的研究。

初高中物理力学实验教学的衔接存在的问题及解决策略

高中物理在新课标实施后;初高中物理力学实验教学的衔接问题很突出。本文对比初高中物理实验中的力学实验进行探究;从教学内容和教学方法上提出解决初高中物理力学实验教学衔接的策略。

借实验之失误巧引智慧之成长——基于物理力学实验的思考

切实针对高中物理学科实验探究课堂教学过程中所遭遇的各类技术失误问题展开系统全面分析,并且找寻和运用针对性的防范控制策略,是保障和支持我国初中阶段物理学科知识内容教学过程中顺利获取到最佳预期效果的重要前提条件,本文围绕高中物理学科实验探究教学环节过程中可能遭遇的技术失误问题及其防范控制要点展开了简要阐释,仅供参考。

弓长岭井下矿矿石力学特性研究

岩石力学是力学和地学相结合形成的一门基础学科,过去,工程中遇到的实际工程问题往往通过经验的方式解决,但工程实践表明,复杂的地质力学条件与岩体力学特性,单纯地靠经验越来越难以适应日益发展的工程规模和工程复杂性。因此,对岩石力学特性进行分析研究,可以更好地把握工程地质条件,根据实际工况做出合理的方案。发展和提高地下矿山精细爆破技术必须对矿山围岩物理力学性质进行研究,通过对现场取样进行物理力学实验,根据得到的实验结果对围岩物理力学特性进行分析研究,从而得到围岩和矿体的物理力学参数,为控制采场爆破机理及控制方法和数值模拟计算奠定基础。

甘庄煤矿高应力巷道锚杆支护参数优化与应用

针对甘庄煤矿高应力巷道原锚杆支护效果不理想的情况,采用煤岩物理力学实验和数值模拟计算等方法,开展锚杆支护参数的优化。通过对不同锚杆间排距、锚杆直径、锚杆长度、锚索间排距的模拟支护效果分析,得出支护方案优化参数:锚杆间排距为900 mm×900 mm、直径为22 mm、长度为2.2 m,锚索间排距为2 000 mm×900 mm。将优化的支护方案进行现场试验,实测表明,巷道顶底板位移量下降了44.1%,两帮位移量下降了41.9%,优化后的锚杆支护系统可以更有效地控制巷道围岩变形,改善了支护效果。

综放工作面煤柱受力特性与稳定性研究

为了给国强煤矿开采4-1号煤提供设计依据,通过建立力学模型研究了综放工作面回采后,煤柱受到采空区一侧引起的支承压力、巷道一侧的支承压力和上部岩层的压力三重作用下的力学特性。研究发现,煤柱在采空区一侧的塑性区宽度与原岩应力、应力集中系数、煤层的内摩擦角、黏聚力、煤层开采厚度等因素有关;巷道一侧煤柱的塑性区宽度与原岩应力、支架阻力、巷道半径以及煤层的内摩擦角、黏聚力等因素相关。在此基础上,通过岩石物理力学实验,获得了煤柱的物理力学参数;通过套孔应力解除法测得了该煤层的原岩应力。根据研究结论和试验结果,得出了国强煤矿4-1号煤层稳定煤柱的宽度为15.4～23.1m。

“一二三四”复习纸带问题

“打点计时器”是“速度随时间变化的规律”“加速度与物体质量、物体受力的关系”“探究动能定理”“验证机械能守恒定律”等多个物理力学实验中的主要器材,关于它的相关问题复习起来比较琐碎.笔者根据教学经验进行了总结分析,意在使问题变得条理清晰,易于掌握.1一条纸带的获得复习时可按“打点计时器的结构”“打点计时器的工作原理”“实验步骤”和“打点计时器操作注意事项”逐一复习.教师可结合打点计时器的实物为学生介绍其结构,指出电磁打点计时器电压是4~6V交流电,电火花打点计时器电压是220V交流电.

重庆市綦江区某水库工程病险整治及新建部分工程地质勘察

重庆市綦江区某水库工程下游坝坡坡面凹凸不平,局部发生变形、失稳现象,不满足大坝稳定要求;需采取工程措施进行除险加固。为配合除险加固工程实施,本文基于实测资料对工程区域工程地质条件,特别是坝体、坝基、坝肩的稳定及岩土体的渗透性进行了勘察、试验、分析,为实例水库工程病险整治及新建部分提供依据。

Simulation of the East Asian Subtropical Westerly Jet Stream with GFDL AGCM (AM2.1)

The present study validated the capability of the AM2.1,a model developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL),in reproducing the fundamental features of the East Asian Subtropical Westerly Jet Stream (EASWJ).The main behaviors of the EASWJ are also investigated through the reanalysis of observational NCEP/NCAR data.The mean state of the EASWJ,including its intensity,location,structure,and seasonal evolution is generally well-portrayed in the model.Compared with the observation,the model tends to reproduce a weaker jet center.And,during summer,the simulated jet center is northward-situated.Results also demonstrate the model captures the variability of EASWJ during summer well.The results of the empirical orthogonal function (EOF) applied on the zonal wind at 200 hPa (U200) over East Asia for both the observation and simulation indicate an inter-decadal shift around the late 1970s.The correlation coefficient between the corresponding principle components is as great as 0.42 with significance at the 99% confidence level.

The Spatial Patterns of Initial Errors Related to the “Winter Predictability Barrier” of the Indian Ocean Dipole

In this study, using the Geophysical Fluid Dynamics Laboratory Climate Model version 2pl （GFDL CM2pl） coupled model, the winter predictability barrier （WPB） is found to exist in the model not only in the growing phase but also the Indian Ocean dipole （IOD） decaying phase of positive events due to the effect of initial errors. In particular, the WPB is stronger in the growing phase than in the decaying phase. These results indicate that initial errors can cause the WPB. The domi- nant patterns of the initial errors that cause the occurrence of the WPB often present an eastern-western dipole both in the surface and subsurface temperature components. These initial errors tend to concentrate in a few areas, and these areas may represent the sensitive areas of the predictions of positive IOD events. By increasing observations over these areas and eliminating initial errors here, the WPB phenomenon may be largely weakened and the forecast skill greatly improved.

Impact of European Black Carbon on East Asian Summer Climate

The remote response of the East Asian summer monsoon （EASM） to European black carbon （EUBC） aerosols was studied by using an ensemble of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory （GFDL） atmospheric general circulation model （AGCM） Atmospheric Model version 2.1 （AM2.1）.The results show that EUBC causes an enhanced EASM.The resulted enhanced southwesterly brings more moisture supply from the Bay of Bengal,which causes an increase in precipitation over the Yangtze River valley,northeastem China,the eastern part of the Yellow River valley,and the Tibetan Plateau.Diagnostic examination suggests that EUBC induces enhanced tropospheric heating over most of the Eurasian Continent through a propagating wave train and horizontal air temperature advection.This phenomenon results in intensified thermal contrast between land and ocean,which accounts for the enhanced EASM.Moreover,reductions in EUBC emission in 1992 may have contributed to decadal weakening of the EASM in the early 1990s.

Study on Hydraulic System Efficiency of Heaving-Buoy Wave Energy Converter

The hydraulic system is the key component in the widely used wave energy converters(WEC).In this paper,we theoretically analyze and describe our investigation of the efficiency of the hydraulic system by simulation and model testing of the combined heaving-buoy WEC.We derive a new governing equation that includes nonlinear hydraulic resistance in the power take-off(PTO).We conducted a physical model experiment based on a 100-kW prototype and applied a hydraulic system with an energy accumulator.The model test results reveal an important parameter related to efficiency with respect to nonlinear hydraulic resistance.We also studied the relationship between the efficiency and the initial conditions.Finally,based on our numerical simulation results,we discuss the effect on efficiency of the gas content of the hydraulic fluid and ways to reduce its impact.

Tropical Pacific Decadal Variability in Subsurface Temperature

The nature decadal variability of the equatorial Pacific subsurface temperature is examined in the control simulation with the Geophysical Fluid Dynamics Laboratory coupled model CM2.1.The dominant mode of the subsurface temperature variations in the equator Pacific features a 20-40 year period and is North-South asymmetric about the equator.Decadal variations of the thermocline are most pronounced in the southwest of the Tropical Pacific.Decadal variation of the north-south asymmetric Sea Surface wind in the tropical Pacific,especially in the South Pacific Convergence,is the dominant mechanism of the nature decadal variation of the subsurface temperature in the equatorial Pacific.

Experimental study on similarity materials for soft rock of deep-buried tunnels

When every parameter is properly scaled down in accordance with some similarity coefficients, it is possible to study the physical-mechanical properties of rock mass with a scale model. To identify the key mechanisms of soft rock in deep buried tunnels, the proper sand, binder and ratio were selected. During the process, the model manufacture technology was introduced and typical tests were done and the results were presented. The physical and meehanieal properties effects caused by each composition were discussed. It is shown that the physical and mechanical properties of chosen ratio material such as uniaxial compressive strength tests, elasticity modulus, tensile strength, internal frictional angle, and Poisson＇s ratio meet with similarity relationship well. The physical and mechanical properties of deep soft rock are simulated successfully.

Adsorption of zinc onto anionic ion-exchange resin from cyanide barren solution

Removal of zinc from cyanide barren solution is obligatory for its reuse in leach process. Batch experiments were carried out to evaluate the adsorption capacity of resins under different experimental conditions, including con- centration, resin amount, initial pH, contact time and temperature. More than 99% of adsorption was achieved under the optimal condition. High adsorption rates on the resin were observed at the beginning and plateau values were obtained in 60 rain. The thermodynamic parameters （free energy change AG, enthalpy change AS and entropy change AH） for the adsorption were evaluated, The adsorption kinetic mechanism was studied with four models. The experimental results show that the adsorption follows the Langmuir isotherm and the kinetics follows the pseudo-second-order model.

Arctic Oscillation Responses to Black Carbon Aerosols Emitted from Major Regions

The responses of the Arctic Oscillation(AO) to global black carbon(BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory(GFDL) atmospheric general circulation model(AGCM) Atmospheric Model version 2.1(AM2.1). The results indicated that global BC could induce positive-phase AO responses, characterized by negative responses over the polar cap on 500 h Pa height fields, and zonal mean sea level pressure(SLP) decreasing while zonal wind increasing at 60°, with the opposite responses over midlatitudes. The AO indices distribution also shifted towards positive values. East Asian BC had similar impacts to that of global BC, while the responses to European BC were of opposite sign. South Asian BC and North American BC did not affect the AO significantly. Based on a simple linear assumption, we roughly estimated that the global BC emission increase could explain approximately 5% of the observed positive AO trend of +0.32 per decade during 1960 to 2000.

深海升温令人惊异

深海升温令人惊异杨平生，张琪海洋学者发现，在１９４２年哥伦布的大西洋航线的深水处，近３５年来海水温度升高了将近０．６华氏度。这一发现对于研究全球气候的变化有重要意义。海洋是气候系统的关键部分，因为海洋吸收、存储、转移并最终释放热量，而热是气候系统的主...

Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios

Many studies have shown that either the nearby astrophysical source or dark matter （DM） annihilation/decay can be used to explain the excess of high energy cosmic ray （CR） e^±which is detected by many experiments, such as PAMELA and AMS-02. Recently, the dark matter particle explorer （DAMPE） collaboration has reported its first result of the total CR e^± spectrum from 25 GeV to 4.6TeV with high precision. In this work, we study the DM annihilation and pulsar interpretations of this result. We show that the leptonic DM annihilation channels to r＋＇/＂-, 4p, 4＂/＇, and mixed charged lepton final states can well explain the DAMPE e^± spectrum. We also find that the mixed charged leptons channel would lead to a sharp drop structure at - TeV. However, the ordinary DM explanations have been almost excluded by the constraints from the observations of gamma-ray and CMB, unless some exotic DM models are introduced. In the pulsar scenario, we analyze 21 nearby known pulsars and assume that one of them dominantly contributes to the high energy CR e^± spectrum. Involving the constraint from the Fermi-LAT observation of the e^± anisotropy, we find that two pulsars could explain the DAMPE e^± spectrum. Our results show that it is difficult to discriminate between the DM annihilation and single pulsar explanations of high energy e^± with the current DAMPE result.